Distributed voltage regulation at a point of load with general power supplied by a power bus is known from the S-100 bus as used in early personal computers like the Altair 8800. Power supplies on the bus were unregulated +8 V and ±18 V, designed to be regulated on the cards to +5 V (used by TTL) and ±12 V (typically used on RS-232 lines or disk drive motors).